Question to the Department of Health and Social Care:

To ask His Majesty's Government whether there are any serious side effects from taking weight-loss drugs, including Wegovy and Mounjaro; and if so, whether those side effects have been made public.

The Medicines and Healthcare products Regulatory Agency (MHRA) continually monitors the safety of all medicines, including weight loss drugs, such as Wegovy (semaglutide) and Mounjaro (tirzepatide), which belong to a group of medicines known as the GLP-1 receptor agonists.

Patient safety is our top priority and no medicine would be approved unless it met our expected standards of safety, quality, and effectiveness. We have robust safety monitoring and surveillance systems in place, and when a safety issue is confirmed, we always act promptly to inform patients and healthcare professionals, and take appropriate steps to mitigate any identified risk.

Importantly, these medicines have been assessed to be safe and effective when used for their licensed indications. This means that if patients have been properly prescribed this by a healthcare professional following a consultation for a medical condition that these medicines are approved to treat, then they should be reassured that the benefits will outweigh risks of taking them.

Like all medicines, GLP-1 receptor agonists can cause side effects. All known side effects for these medicines, including serious side effects, are made publicly available through the Product Information. This is issued at the time of licensing, and is updated as any new side effects are identified. This includes the Summary of Product Characteristics, which is intended for healthcare professionals, and the Patient Information Leaflet, which is provided to patients. These documents are published on the products section of the MHRA website.

In addition, members of the public and healthcare professionals can access anonymised data on suspected side effects reported to the Yellow Card scheme via the interactive Drug Analysis Profiles platform. This ensures full transparency and enables anyone to view the types and numbers of suspected adverse reactions reported for a particular medicine.

Some of the most common side effects are gastrointestinal effects, such as nausea, vomiting, and diarrhoea. These side effects were observed in clinical trials and make up the majority of Yellow Card reports we receive. Most side effects are mild to moderate in severity or short in duration, but in some cases, they may lead to complications, such as severe dehydration resulting in the need to go to hospital for treatment.

Although infrequent, inflammation of the pancreas, known as acute pancreatitis, has also been reported. This can be serious. The main symptom is severe pain in the stomach that radiates to the back and does not go away. Anyone who experiences this should seek immediate medical help and report the reaction to the MHRA’s Yellow Card scheme.